(meteorobs) Meteor Activity Outlook for April 6-12, 2007

Robert Lunsford lunro.imo.usa at cox.net
Fri Apr 6 15:59:45 EDT 2007


April has one major annual shower and the start of another. The Lyrids are
active from April 16-25 and reach maximum activity on the 22nd. While not
the strongest annual shower they produce much better rates than has been
seen for the past three months. The Eta Aquarids also reach a ZHR of one on
April 19 and slowly continue to increase in strength as the month
progresses. Sporadic rates seen in the northern hemisphere are actually
worse than those seen in March. This trend will continue through June. On
the other hand rates seen from the southern hemisphere are increasing toward
a July maximum.

During this period the moon reaches its last quarter phase on Tuesday April
10. At this time the moon will rise near 0100 and will be in the sky the
remainder of the morning. One can still hold successful observations simply
by keeping the moon out of your field of view. The estimated total hourly
rates for evening observers this week is near two for those north of the
equator and three for observers south of the equator. For morning observers
the estimated total hourly rates should be near six for northern observers
and twelve for those south of the equator. These rates assume that you are
watching from rural areas away from all sources of light pollution. The
actual rates will also depend on factors such as personal light and motion
perception, local weather conditions, alertness and experience in watching
meteor activity. Morning rates are reduced due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning April 7/8. These positions do not change greatly day to day so the
listed coordinates may be used during this entire period. Most star atlases
(available at science stores and planetariums) will provide maps with grid
lines of the celestial coordinates so that you may find out exactly where
these positions are located in the sky. A planisphere or computer
planetarium program is also useful in showing the sky at any time of night
on any date of the year. Activity from each radiant is best seen when it is
positioned highest in the sky, either due north or south along the meridian,
depending on your latitude. It must be remembered that meteor activity is
rarely seen at the radiant position. Rather they shoot outwards from the
radiant so it is best to center your field of view so that the radiant lies
at the edge and not the center. Doing this will allow you to easily trace
the path of each meteor back to the radiant (if it is a shower member) or in
another direction if it is a sporadic. Meteor activity is not seen from
radiants that are located below the horizon. The positions below are listed
in a west to east manner in order of right ascension (celestial longitude).
The positions listed first are located further west therefore are accessible
earlier in the night while those listed further down the list rise later in
the night.

The Antihelion (ANT) radiant is now centered at 14:04 (211) -12. This area
of the sky is centered in southeastern Virgo, three degrees southwest of the
fourth magnitude star Kappa Virginis. This radiant is best placed near 0200
LDT when it lies on the meridian and is highest in the sky. Rates at this
time should be near two per hour no matter your location. With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

Sporadic rates are slowing decreasing for observers in the northern
hemisphere and slightly rising for those south of the equator. One would
expect to see perhaps six random meteors during the last hour before dawn
from rural observing sites located in the northern hemisphere. During the
first dark hour after the end of evening twilight, perhaps two random
meteors can be seen per hour. Sporadic rates increase as the night
progresses so rates seen near midnight would be near four per hour. Late
morning sporadic rates seen from the southern hemisphere are now near a ten
per hour from rural observing sites. During the first dark hour after the
end of evening twilight, perhaps three random meteors can be seen per hour,
increasing to eight by midnight. Morning rates are reduced due to moonlight.

Antihelion (ANT) - 14:04 (211) -12
Northern Hemisphere - 2  Southern Hemisphere - 2

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2006

Clear Skies!
Robert Lunsford
American Meteor Society



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